Silence 2019/mills in linux (clang)

The warning -Wunsafe-buffer-usage is triggered (iirc) on pretty much
every use of 'char *' and some of the previous commits also had to
silence this warning. It is triggered by clang -Weverything.

2019/mills/Makefile

@@ -40,7 +40,7 @@ include ../../var.mk
 #
 CSILENCE= -Wno-for-loop-analysis -Wno-missing-field-initializers \
 	  -Wno-strict-prototypes -Wno-misleading-indentation \
-	  -Wno-old-style-declaration -Wno-unused-value
+	  -Wno-old-style-declaration -Wno-unused-value -Wno-unsafe-buffer-usage
 
 # Attempt to silence unknown warnings
 #